Anti-bounce control system for a machine

ABSTRACT

A system for automated control of a motor grader includes a first sensor to indicate bounce of the motor grader and a speed sensor to indicate the ground speed. A controller determines a maximum amplitude of the bounce of the motor grader and controls the ground speed of the motor grader at least in part based upon the maximum amplitude of the bounce. A method is also provided.

This is a continuation of application Ser. No. 13/465,875, filed May 7,2012, the disclosure of which is incorporated by reference.

TECHNICAL FIELD

This disclosure relates generally to controlling a machine and, moreparticularly, to a control system for reducing harmonic vibrations ofthe machine.

BACKGROUND

Certain machines such as motor graders have a natural frequency that maynegatively affect their operation due to resonance at such naturalfrequency. The natural frequency of a motor grader is a function ofnumerous physical characteristics of the machine such as its weightdistribution, the distance between the rear wheels and the moldboard,and the tire characteristics. In addition, the operating conditionsencountered by the motor grader may also affect the natural frequency.Excitation at the natural frequency may result in harmonic vibrationswithin the motor grader commonly referred to as “bounce.”

Harmonic vibrations or bounce typically occur when the motor grader isoperated within a particular range of speeds and with a light load onthe blade or moldboard. The movement caused by the bouncing conditionmay interrupt the contact between a work surface and the moldboard whichmay result in an uneven finish or scallop on the work surface. Such anuneven finish may require reworking of the work surface or theapplication of additional material for proper finishing.

Motor graders may experience three different types of harmonicvibrations or bounce: pitching, side-to-side or “duck-walk,” andvertical vibrations or bounce. Each of these types of harmonicvibrations or bounce conditions may negatively impact a gradingoperation. Harmonic vertical movement or bounce generally occurs at afrequency between 1.5 and 3 Hz.

U.S. Patent Publication No. 2010/0051298 A1 discloses a system fordetecting and dissipating hydraulic spikes in pressure caused whenimplements of a machine bounce. The pressure spikes are dissipated bygenerating random or canceling pulses within the hydraulic system.

The foregoing background discussion is intended solely to aid thereader. It is not intended to limit the innovations described herein,nor to limit or expand the prior art discussed. Thus, the foregoingdiscussion should not be taken to indicate that any particular elementof a prior system is unsuitable for use with the innovations describedherein, nor is it intended to indicate that any element is essential inimplementing the innovations described herein. The implementations andapplication of the innovations described herein are defined by theappended claims.

SUMMARY

The disclosure describes, in one aspect, a system for automated controlof movement of a motor grader having a prime mover and a ground engagingblade. A first sensor is disposed on the motor grader and is configuredto provide a bounce signal indicative of a measured bounce of the motorgrader. A speed sensor is disposed on the motor grader and is configuredto provide a speed signal indicative of a ground speed of the motorgrader. A controller is configured to receive the bounce signal from thefirst sensor and determine a maximum amplitude of the measured bounce ofthe motor grader based upon the bounce signal. The controller is furtherconfigured to generate a command signal to control the ground speed ofthe motor grader at least in part based upon the maximum amplitude ofthe measured bounce and transmit the command signal to change the speedof the motor grader.

In another aspect, the disclosure describes a controller implementedmethod of adjusting movement of a motor grader having a prime mover, aground engaging blade, a first sensor configured to provide a bouncesignal indicative of a measured bounce of the motor grader, and a speedsensor disposed on the motor grader configured to provide a speed signalindicative of a ground speed of the motor grader. The method includesreceiving the bounce signal from the first sensor and determining amaximum amplitude of the measured bounce of the motor grader based uponthe bounce signal. The method further includes generating a commandsignal within the controller to control the ground speed of the motorgrader at least in part based upon the maximum amplitude of the measuredbounce and transmitting the command signal from the controller to changethe speed of the motor grader.

In still another aspect, the disclosure describes a motor graderincluding a prime mover, a ground engaging blade, a first sensor isdisposed on the motor grader and is configured to provide a bouncesignal indicative of a measured bounce of the motor grader, and a speedsensor is disposed on the motor grader and is configured to provide aspeed signal indicative of a ground speed of the motor grader. Acontroller is configured to receive the bounce signal from the firstsensor and determine a maximum amplitude of the measured bounce of themotor grader based upon the bounce signal. The controller is furtherconfigured to generate a command signal to control the ground speed ofthe motor grader at least in part based upon the maximum amplitude ofthe measured bounce and to transmit the command signal to change thespeed of the motor grader.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a motor grader constructed inaccordance with the disclosure;

FIG. 2 is a block diagram of an anti-bounce control system in accordancewith the disclosure;

FIG. 3 is a flowchart illustrating an anti-bounce control process inaccordance with the disclosure;

FIG. 4 is an exemplary graph of a simulation of vertical bounce of amotor grader;

FIG. 5 is an exemplary graph depicting a simulation of gas pedaldisplacement corresponding to the vertical bounce depicted in FIG. 5;

FIG. 6 is an enlarged view of the portion identified at 6 in FIG. 4;

FIG. 7 is an enlarged view of the portion identified at 7 in FIG. 5;

FIG. 8 is an exemplary graph, similar to FIG. 6, depicting simulatedvertical bounce of a motor grader incorporating the anti-bounce controlsystem in accordance with the disclosure; and

FIG. 9 is an exemplary graph, similar to FIG. 7, depicting a simulationof a gas pedal displacement command from an operator as well as acommand generated by the anti-bounce control system when overriding theoperator command.

DETAILED DESCRIPTION

FIG. 1 is a diagrammatic illustration of machine such as a motor grader10 that may be used in accordance with an embodiment of the disclosure.The motor grader 10 includes a frame 11 and a prime mover such as anengine 12. A set of front wheels 13 may be operatively connected to theframe 11 generally adjacent a front end of the motor grader 10 and twosets of rear wheels 14 may be operatively connected to the frame 11generally adjacent a rear end of the motor grader. In an alternateembodiment, only a single set of rear wheels 14 may be provided. One orboth sets of rear wheels 14 may be powered by a power transfer mechanism(not shown) operatively connected to the engine 12. The power transfermechanism may be any desired type of drive system including ahydrostatic propulsion system, an electric drive system or a mechanicaldrive system. An operator cab 15 may be mounted on the frame 11 andincludes various controls, sensors and other mechanisms used by anoperator.

A blade or moldboard 20 extends downward from the frame 11. Themoldboard 20 may be mounted on a blade tilt adjustment mechanism 21 thatis supported by a rotatable circle assembly 22 operatively connected tothe blade tilt adjustment mechanism 21. A variety of hydraulic cylindersor other mechanisms may be provided for controlling the position of themoldboard 20. For example, circle assembly 22 may be supported by a pairof blade lift actuators 23 (with only one visible in FIG. 1). Adjustmentof the blade lift actuators 23 allows the height of rotatable circleassembly 22, and hence the height of moldboard 20, to be adjusted. Bladelift actuators 23 may be moved independently or in combination with eachother. A center shift cylinder 24 may be provided to shift the circleassembly 22 from side-to-side. A blade tip cylinder 25 may be providedto control the angle between an edge of the moldboard 20 and the ground.One or more side shift cylinders (not shown) may be provided to controllateral movement of the moldboard 20 relative to the circle assembly 22.The circle assembly 22 may include a mechanism such as gear teeth toallow rotation of the moldboard 20. Other manners of positioning andcontrolling the moldboard 20 may be utilized if desired.

Motor grader 10 may be equipped with a plurality of sensors that providedata indicative (directly or indirectly) of the performance orconditions of various aspects of the machine. An operator presencesensor 30 may be provided to sense whether an operator is seated withinthe operator cab 15. A parking brake sensor 31 may be provided to sensewhether the parking brake is engaged. A transmission output speed sensor32 may be provided for sensing the output speed from a transmission (notshown). A wheel speed sensor 33 may be provided for sensing the speed ofthe rear wheels 14 and thus indicate the ground speed of the motorgrader 10.

One or more bounce sensors may be provided for sensing the bounce ormovement of the motor grader 10. In one embodiment, a first sensor suchas an accelerometer 34 may be provided on motor grader 10. The firstsensor may be used to provide an acceleration signal indicative ofmeasured acceleration of the motor grader 10 relative to a gravityreference. In one example, the first sensor may provide measurements insix degrees of freedom (i.e., fore-aft, lateral, and vertical directionsas well as pitch, roll and yaw). In an alternate embodiment, the firstsensor may be a three-axis accelerometer providing an accelerationsignal indicative of measured acceleration of the motor grader alongfore-aft, lateral and vertical directions. In another alternateembodiment, the first sensor may be a single-axis accelerometerproviding the measurement of the mixed acceleration of the motor graderalong fore-aft, lateral and vertical directions. By monitoring theacceleration at the first sensor, movements of the motor grader 10 maybe detected that are indicative of motor grader bounce. In somecircumstances, it may be desirable to place the first sensor generallyadjacent the rear wheels 14. Still further, it may be desirable toposition the first sensor generally adjacent operator cab 15 so thatmovement sensed by the first sensor somewhat matches movement sensed bythe operator.

In another alternate configuration, the first sensor may include one ormore hydraulic pressure sensors 35 associated with some or all of thehydraulic cylinders that are used to control the moldboard 20, the bladetilt adjustment mechanism 21 and the circle assembly 22. By monitoringthe pressure and pressure changes in the cylinders, specific pressurecharacteristics may be monitored that are indicative of motor graderbounce. Other types of sensors are also contemplated.

A control system 40 may be provided to control the operation of themotor grader 10 including the anti-bounce control aspects orfunctionality of the machine. The control system 40, as shown generallyby an arrow in FIG. 1 indicating association with the motor grader 10,may include an electronic control module such as controller 41. Thecontroller 41 may receive operator input command signals and control theoperation of the various systems of the motor grader 10. The controller41 is shown in FIG. 1 residing in the operator cab 15 but may be mountedat any convenient location on motor grader 10. The control system 40 mayinclude one or more input devices (not shown) to control the motorgrader 10 and one or more sensors, including the operator presencesensor 30, the parking brake sensor 31, the transmission output speedsensor 32, the wheel speed sensor 33, and the first sensor, to providedata and other input signals representative of various operatingparameters of the motor grader 10.

The controller 41 may be an electronic controller that operates in alogical fashion to perform operations, execute control algorithms, storeand retrieve data and other desired operations. The controller 41 mayinclude or access memory, secondary storage devices, processors, and anyother components for running an application. The memory and secondarystorage devices may be in the form of read-only memory (ROM) or randomaccess memory (RAM) or integrated circuitry that is accessible by thecontroller. Various other circuits may be associated with the controllersuch as power supply circuitry, signal conditioning circuitry, drivercircuitry, and other types of circuitry.

The controller 41 may be a single controller or may include more thanone controller disposed to control various functions and/or features ofthe motor grader 10. The term “controller” is meant to be used in itsbroadest sense to include one or more controllers and/or microprocessorsthat may be associated with the motor grader 10 and that may cooperatein controlling various functions and operations of the machine. Thefunctionality of the controller 41 may be implemented in hardware and/orsoftware without regard to the functionality. The controller 41 may relyon one or more data maps relating to the operating conditions of themotor grader 10 that may be stored in the memory of controller. Each ofthese maps may include a collection of data in the form of tables,graphs, and/or equations. The controller 41 may use the data maps tomaximize the efficiency of the motor grader 10.

The control system 40 may include an anti-bounce control system orfunctionality for assisting in controlling certain types of harmonicmovement of the motor grader 10 known as bounce. In doing so, thecontroller 41 may be configured to receive as input values theamplitudes of movement of the motor grader 10 at certain frequencies atwhich bounce is likely to occur. Threshold values of the amplitude ofthe motor grader movement at each of specified or predeterminedfrequencies may be stored as a portion of the data maps to assist indetermining the existence of a bounce condition. Maps of responses tomotor grader bounce exceeding the threshold value may be established andstored within the controller 41. Such maps may utilize various factorsincluding the speed of the motor grader 10, the extent to which theamplitude of the bounce exceeds the threshold value, and the frequencyof the bounce condition. Other operating conditions and characteristicsof the motor grader 10 may also be related in the data maps.

During the operation of the motor grader 10, as described in more detailbelow, the anti-bounce control functionality of control system 40 maymodify the operating conditions of the motor grader to eliminate orreduce motor grader bounce. In one example, once the controller 41determines that a bounce condition exists, it may override the gas pedalcontrol command directed by the operator so as to reduce the enginespeed and thus reduce the speed of the motor grader 10. Once the bouncecondition has been sufficiently eliminated or reduced, the anti-bouncecontrol functionality of the control system 40 is disengaged and nolonger affects the operation of the engine 12 so that the engine speedis returned to that directed by the operator.

As depicted in FIG. 2, the controller 41 receives information fromvarious sensors and systems of the motor grader 10 and processes thisinformation. Controller 41 may receive, at a node 43, a bounce signal orsignals from a bounce sensor indicative of the bounce of the motorgrader 10. The bounce sensor may be the first sensor such as anaccelerometer 34 or hydraulic pressure sensors 35 on the hydrauliccylinders associated with the moldboard 20. At node 44, the controller41 may receive a signal as to which gear has been selected by theoperator for operating the motor grader 10. Such signal may be generatedby another aspect of the control system that controls the operation ofthe transmission of the motor grader 10. At node 45, the controller 41may receive a signal as to whether an operator is seated within theoperator cab 15. The operator presence signal may be provided byoperator presence sensor 30.

The controller 41 may receive a signal at node 46 as to whether theparking brake is engaged. The parking brake signal may be provided by aparking brake sensor 31. At node 47, the controller 41 may receive asignal as to the status of certain diagnostics of the anti-bouncecontrol system. At node 48, the controller 41 may receive a signalindicative of the wheel speed of the front or rear wheels 14. The wheelspeed signal may be provided by the wheel speed sensor 33. At node 49,the controller 41 may receive a signal as to the status of the varioussensors that provide information to the anti-bounce control system. Atnode 50, the controller 41 may receive a signal from a user switch 36 asto whether the operator has engaged or disengaged the anti-bouncecontrol system.

In one embodiment, the controller 41 may generate various output signalsbased upon the operation of the anti-bounce control system. At node 51,the controller 41 may provide a command signal such as an engine speedcontrol command to control operation of the engine speed. The controller41 made provide a signal at node 52 to communicate to other aspects ofthe control system 40 the status of the anti-bounce control system.

At node 53, the controller 41 may provide a signal to an indicator light(not shown) indicating whether the anti-bounce control functionality isin operation. For example, if the motor grader 10 is not in a bouncecondition, the light may be off. If the motor grader 10 is experiencingbounce and the anti-bounce control functionality is operating, the lightmay be illuminated. If the motor grader 10 is in a bounce condition butthe anti-bounce control functionality is not operating, the light may beflashing. Examples of when the motor grader 10 may be in a bouncecondition but the anti-bounce control functionality is not operatinginclude when the operator has turned off the anti-bounce controlfunctionality or when other systems of the motor grader 10 that controlthe engine speed have a higher priority and take precedence over theanti-bounce control functionality.

Motor grader 10 may be equipped with a user interface 36 to activate anddeactivate the anti-bounce control system of the control system 40. Thisuser interface could be a switch or touch screen. If the user interface36 is not activated, motor grader 10 will operate in accordance with theoperator's commands regardless of the operating conditions encounteredby the motor grader.

If the user interface 36 is activated, the control system 40 willoperate in accordance with the flow chart of FIG. 3. The controller 41may initially perform various diagnostic and system checks at stage 60to determine that the anti-bounce control system and components of themotor grader 10 are operating properly. If any aspects of the system orcomponents of motor grader 10 are not operating properly, controllerwill not activate the anti-bounce control functionality and the motorgrader 10 will operate in accordance with the operator's commands evenif bounce conditions are encountered.

At stage 61, the controller 41 determines whether certain thresholdconditions of the anti-bounce control system have been met. For example,the anti-bounce control functionality may only be operative undercertain operating conditions of the motor grader 10. One requiredoperating condition may be that the transmission output speed must bewithin a predetermined range. An additional operating condition may bethat the transmission is operating in certain predetermined gears. Forexample, bounce typically occurs and needs to be controlled to reducethe damage to the ground by the blade when the motor grader 10 istraveling between approximately 6-9 miles per hour. Accordingly, for amotor grader 10 having a transmission (not shown) with eight forwardgears, the anti-bounce control functionality may only be operative whenthe transmission is in either the third or fourth gear. Operation ineither the first or second gear may be too slow to create a bouncecondition. Operation at the fifth gear and above may be too fast for theoperator to conduct high quality grading work. As a result, it isunlikely that high quality grading work will be impacted if bounceconditions occur at such higher speed.

Additional required operating conditions may include the presence of anoperator in the operator's seat and the disengagement of the parkingbrake. Still further, the wheel speed sensor 33 may provide a speedsignal indicative of the ground speed of the motor grader 10. The speedsignal may be monitored and the anti-bounce control system may functiononly if the wheel speed is below a predetermined threshold. For example,the controller 41 may be configured so that the anti-bounce controlfunctionality is inoperative when the wheel speed is above approximately10.5 miles per hour. At relatively high speeds (such as those above 10.5miles per hour), the motor grader 10 is unlikely to be performinggrading operations and is unlikely to encounter bounce conditions thatnegatively impact contact between the work surface and the moldboard 20.

The system may be configured so that the anti-bounce controlfunctionality will be inoperative if any of the threshold conditions arenot met. In other circumstances, the anti-bounce control functionalitymay be limited or otherwise adjusted depending on which thresholdconditions have not been met.

If the system threshold conditions have been met at stage 61, thecontroller 41 receives at stage 62 bounce signals from the first orbounce sensors (such as an accelerometer 34 or hydraulic pressuresensors 35) that are indicative of movement of the motor grader 10. Itshould be noted that the natural frequency of each motor grader 10 is afunction of numerous characteristics including weight and weightdistribution, machine dimensions, and the tire characteristics. Thisbounce at the natural frequency could be triggered by various operatingconditions encountered by the motor grader 10 (such as soil conditionsand profile, blade movement, and gear and speed changes). Accordingly,when analyzing movement of the motor grader 10 for bounce, thecontroller 41 analyzes, at stage 63, the amplitude of movement of themotor grader 10 within certain frequency ranges.

In an example of vertical bounce of a motor grader 10, the controller 41may analyze vertical movement of the motor grader 10 within a frequencyrange of between approximately 1.5 and 3 Hz. When performing suchanalysis, the controller 41 may analyze at stage 64 the amplitude ofvertical movement at each frequency within the range and determine themaximum amplitude of movement as well as the frequency of such maximummovement.

In examples of both pitch and side-to-side bounce, the frequency rangeanalyzed by the controller 41 may overlap with or be different from thefrequency range of the vertical bounce. For each type of movement, thecontroller 41 may analyze at stage 64 the amplitude of the particularmovement at each frequency within the range and determine the maximumamplitude of the movement as well as the frequency of such maximummovement.

At stage 65, the controller determines whether the maximum amplitude ofmovement exceeds a predetermined threshold. In one example, this may becarried out by comparing the maximum amplitude to data maps within thecontroller 41 corresponding to the specific frequency. If the maximumamplitude does not exceed the predetermined threshold, the anti-bouncecontrol functionality is not activated and the motor grader 10 willoperate in accordance with the operator's commands as any bounceconditions encountered are insufficient to warrant the anti-bouncecontrol system overriding the operator commands.

If the maximum amplitude does exceed the predetermined threshold, thecontroller 41 may determine at stage 66 whether any other subsystemswithin control system 40 have priority over the anti-bounce controlfunctionality. If the anti-bounce control functionality is beingoverriden, the motor grader 10 will operate without the anti-bouncecontrol functionality. The controller may, at stage 67, generate asignal indicating that the motor grader 10 is operating in a bouncecondition but the anti-bounce control functionality has been overriden.This may be indicated by a flashing indicator light within the operatorcab 15.

If the anti-bounce control functionality is not being overriden at stage66, the controller may, at stage 68, determine the appropriate action toeliminate the bounce condition and generate an appropriate commandsignal. In one example, the controller 41 may generate a command signalto reduce the speed of the engine 12 to slow down the motor grader 10.In another example, the command signal from the controller 41 may applythe service brakes of the motor grader 10. Other manners of reducing thespeed of the motor grader 10 may be used. In some circumstances, it maybe possible to terminate the bounce condition by increasing the speed ofthe motor grader 10. In such an example, the command signal from thecontroller 41 may increase the speed of the engine 12. The commandsignal generated by the controller may be based upon the operatingconditions of the motor grader 10 as well as the amplitude and frequencyof the bounce. For example, the controller 41 may reduce the enginespeed substantially more quickly for a bounce condition that issubstantially greater than the threshold condition as compared to abounce condition that slightly exceeds the threshold condition.

The controller may, at stage 69, generate a signal indicating that themotor grader 10 is operating in a bounce condition and that theanti-bounce control functionality is operating. This may be indicated byenergizing an indicator light within the operator cab 15. Aftergenerating the command signal, the command signal may be transmitted tothe appropriate system at stage 70 to reduce or eliminate the bouncecondition.

It should be noted that, as described above, motor grader 10 mayexperience three different types of bounce conditions (i.e., vertical,pitch and side-to-side) and at three frequencies. In other words,vertical bounce occurs in a first direction and at a first frequency,bounce in a pitch direction occurs in a second direction and at a secondfrequency, and side-to-side bounce occurs in a third direction and at athird frequency. They may not occur at identical frequencies. The datamaps of controller 41 may contain data for each type of bounce and theprocess set forth in FIG. 3 repeated (simultaneously or sequentially)for each type of bounce. In doing so, controller 41 may determine acommand signal to reduce or eliminate each type of bounce but onlytransmit the command signal to reduce the largest bounce.

In an alternate configuration, the controller 41 may determine, basedupon the operating conditions and input from the three types of bounce,that an alternate or blended solution may be desirable to reduce oreliminate the bounce. In another alternate configuration, the controller41 may generate a command signal that reduces each type of bouncewithout immediately eliminating any type of bounce. In still anotheralternate configuration, one type of bounce may be deemed moredetrimental than another so that the controller prioritizes thegeneration of command signals to reduce or eliminate a particular typeof bounce first. Such prioritization may also be dependent upon therelative amplitudes or the degree to which each type of bounce exceedsits respective threshold.

Referring to FIG. 4, a graph of simulated vertical machine accelerationor bounce 75 of a motor grader 10 is depicted as a function of time.FIG. 5 depicts a simulated gas pedal displacement command 76 from anoperator corresponding to the graph of FIG. 4 depicted as a percentageof possible gas pedal movement as a function of time and without theanti-bounce control functionality of control system 40. FIG. 6 is anenlarged view of the section of the graph of FIG. 4 within the boxlabeled 6, and FIG. 7 is an enlarged view of the section of the graph ofFIG. 5 within the box labeled 7.

In FIGS. 5 and 7, it may be seen that as the motor grader begins tovertically bounce, the operator may attempt to reduce the bounce bymanually reducing the displacement of the gas pedal. However, referringto FIGS. 6-7, it may be seen that the vertical bounce begins to takeeffect slightly prior to approximately 60 seconds along the graph andthe operator does not act to reduce the gas pedal displacement at 77until approximately 67 seconds along the graph. The vertical bouncebegins to decrease and the operator increases the gas pedal displacementat 78 corresponding to approximately 72 seconds along the graph.However, the vertical bounce may not have been sufficiently reducedand/or the increase in engine speed causes the motor grader 10 to beginto bounce again at approximately 80 seconds along the graph. Theoperator then reduces the gas pedal displacement at 79 corresponding toapproximately 87 seconds along the graph to reduce the vertical bounce.At approximately 92 seconds along the graph, the bounce is reduced andthe operator increases the gas pedal displacement at 80. In thesimulation depicted in FIG. 7, the motor grader 10 experienced verticalbounce for approximately 30 seconds as the operator made repeatedattempts to reduce the bounce.

FIGS. 8-9 depict a simulation of vertical bounce 81 of motor grader 10and gas pedal displacement 82, respectively, with the anti-bouncecontrol functionality of control system 40 operational. As the verticalbounce begins to take effect slightly prior to approximately 60 secondsalong the graph, the anti-bounce control functionality of control system40 overrides the gas pedal command from the operator and automaticallyreduces the gas pedal displacement at 83.

The anti-bounce control system then maintains the reduced gas pedalcommand and subsequently increases the command at 84 corresponding toapproximately 63 second on the graph until the gas pedal command returnsto the operator gas pedal command at 85 corresponding to approximately66 seconds on the graph. It may be seen by comparing FIGS. 7 and 9 thatthe automated control provided by the control system 40 reduces the gaspedal displacement earlier than the operator and reduces the gas pedalcommand less abruptly, but also reduces the gas pedal command by agreater amount. As depicted in FIG. 8, the motor grader 10 experiencesvertical bounce for a significantly shorter time period with theanti-bounce control system engaged. It should be noted that although thegas pedal displacement is greater in the example depicted in FIG. 9 ascompared to FIG. 7, the rate of the reduction is less in FIG. 9 so thatthe operator may perceive a smaller decrease in engine and motor graderspeed.

Although the anti-bounce control system is described above relative tocontrolling bounce conditions to minimize damage to a ground surface, insome situations, it may be desirable to utilize the system when themoldboard 20 is not engaging the ground. For example, a bounce conditionmay occur when the motor grader 10 is traveling at relatively highspeeds and the moldboard is above the ground surface. In such case, theanti-bounce control system may be used to reduce the bounce conditionand thus increase the comfort of the operator without affecting theground surface.

INDUSTRIAL APPLICABILITY

The industrial applicability of the system described herein will bereadily appreciated from the foregoing discussion. The foregoingdiscussion is applicable to machines such as motor graders 10 for whichharmonic vibrations or bounce may affect their operation. Individualcharacteristics of the machine as well as the operating conditions andenvironment affect the natural frequency of each machine. Theanti-bounce control system disclosed herein determines the naturalfrequency of the motor grader 10 by analyzing movement of the motorgrader, determining the maximum amplitude of movement and the frequencyat which such movement occurs. The controller 41 may then reduce oreliminate the bounce by changing the speed of the motor grader 10 basedupon various factors such as the amplitude of the bounce and the naturalfrequency of the motor grader as well as the operating conditions andother factors, if desired.

In one aspect, a system is described for automated control of movementof a motor grader 10 having a prime mover and a ground engaging blade. Afirst sensor is disposed on the motor grader 10 and is configured toprovide a bounce signal indicative of a measured bounce of the motorgrader. A speed sensor is disposed on the motor grader 10 and isconfigured to provide a speed signal indicative of a ground speed of themotor grader. A controller 41 is configured to receive the bounce signalfrom the first sensor and determine a maximum amplitude of the measuredbounce of the motor grader 10 based upon the bounce signal. Thecontroller 41 is further configured to generate a command signal tocontrol the ground speed of the motor grader 10 at least in part basedupon the maximum amplitude of the measured bounce and to transmit thecommand signal to change the speed of the motor grader.

In another aspect, the disclosure describes a controller implementedmethod of adjusting movement of a motor grader 10 having a prime mover,a ground engaging blade, a first sensor configured to provide a bouncesignal indicative of a measured bounce of the motor grader, and a speedsensor disposed on the motor grader configured to provide a speed signalindicative of a ground speed of the motor grader. The method includesreceiving the bounce signal from the first sensor and determining amaximum amplitude of the measured bounce of the motor grader 10 basedupon the bounce signal. The method further includes generating a commandsignal within the controller 41 to control the ground speed of the motorgrader 10 at least in part based upon the maximum amplitude of themeasured bounce and transmitting the command signal from the controller41 to change the speed of the motor grader.

In still another aspect, the disclosure describes a motor grader 10including a prime mover, a ground engaging blade, a first sensor isdisposed on the motor grader and is configured to provide a bouncesignal indicative of a measured bounce of the motor grader, and a speedsensor is disposed on the motor grader and is configured to provide aspeed signal indicative of a ground speed of the motor grader. Acontroller 41 is configured to receive the bounce signal from the firstsensor and determine a maximum amplitude of the measured bounce of themotor grader 10 based upon the bounce signal. The controller is furtherconfigured to generate a command signal to control the ground speed ofthe motor grader at least in part based upon the maximum amplitude ofthe measured bounce and to transmit the command signal to change thespeed of the motor grader.

It will be appreciated that the foregoing description provides examplesof the disclosed system and technique. However, it is contemplated thatother implementations of the disclosure may differ in detail from theforegoing examples. All references to the disclosure or examples thereofare intended to reference the particular example being discussed at thatpoint and are not intended to imply any limitation as to the scope ofthe disclosure more generally. All language of distinction anddisparagement with respect to certain features is intended to indicate alack of preference for those features, but not to exclude such from thescope of the disclosure entirely unless otherwise indicated.

Recitation of ranges of values herein are merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein, and eachseparate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context.

Accordingly, this disclosure includes all modifications and equivalentsof the subject matter recited in the claims appended hereto as permittedby applicable law. Moreover, any combination of the above-describedelements in all possible variations thereof is encompassed by thedisclosure unless otherwise indicated herein or otherwise clearlycontradicted by context.

1. A system for automated control of movement of a motor grader, themotor grader including a prime mover and a ground engaging blade,comprising: a first sensor disposed on the motor grader configured toprovide a bounce signal indicative of a measured bounce of the motorgrader; a speed sensor disposed on the motor grader configured toprovide a speed signal indicative of a ground speed of the motor grader;and a controller configured to: receive the bounce signal from the firstsensor; determine a maximum amplitude of the measured bounce of themotor grader based upon the bounce signal; and generate a command signalto apply a brake at least in part based upon the maximum amplitude ofthe measured bounce, the brake reducing the ground speed of the motorgrader.
 2. The system of claim 1, wherein the controller is furtherconfigured to determine the maximum amplitude of the measured bounce ina first direction and within a first frequency range.
 3. The system ofclaim 2, wherein the controller is further configured to determine themaximum amplitude of the measured bounce in a second direction andwithin a second frequency range.
 4. The system of claim 3, wherein thefirst frequency range is different from the second frequency range. 5.The system of claim 3, wherein the controller is further configured todetermined the maximum amplitude of the measured bounce in a thirddirection and within a third frequency range.
 6. The system of claim 1,wherein the command signal reduces the speed of the prime mover.
 7. Acontroller implemented method of adjusting movement of a motor grader,the motor grader having a prime mover, a ground engaging blade, a firstsensor configured to provide a bounce signal indicative of a measuredbounce of the motor grader, and a speed sensor disposed on the motorgrader configured to provide a speed signal indicative of a ground speedof the motor grader, comprising: receiving the bounce signal from thefirst sensor; determining a maximum amplitude of the measured bounce ofthe motor grader based upon the bounce signal; and generating a commandsignal within the controller to apply a brake at least in part basedupon the maximum amplitude of the measured bounce, the brake reducingthe ground speed of the motor grader.
 8. The controller implementedmethod of claim 7, further including determining the maximum amplitudeof the measured bounce in a first direction and within a first frequencyrange.
 9. The controller implemented method of claim 8, furtherincluding determining the maximum amplitude of the measured bounce in asecond direction and within a second frequency range.
 10. The controllerimplemented method of claim 7, further including reducing the speed ofthe prime mover.
 11. A motor grader comprising: a prime mover; a groundengaging blade; a first sensor disposed on the motor grader configuredto provide a bounce signal indicative of a measured bounce of the motorgrader; a speed sensor disposed on the motor grader configured toprovide a speed signal indicative of a ground speed of the motor grader;and a controller configured to: receive the bounce signal from the firstsensor; determine a maximum amplitude of the measured bounce of themotor grader based upon the bounce signal; and generate a command signalto apply a brake at least in part based upon the maximum amplitude ofthe measured bounce, the brake reducing the ground speed of the motorgrader.
 12. The motor grader of claim 11, wherein the controller isfurther configured to determine the maximum amplitude of the measuredbounce in a first direction and within a first frequency range.
 13. Themotor grader of claim 12, wherein the controller is further configuredto determine the maximum amplitude of the measured bounce in a seconddirection and within a second frequency range.
 14. The system of claim1, wherein the controller is further configured to receive anoperator-generated prime mover command signal from an operator and thecommand signal generated by the controller temporarily overrides theoperator-generated prime mover command signal.
 15. The system of claim14, wherein the controller temporarily overrides the operator-generatedprime mover command signal while the measured bounce exceeds apredetermined value.
 16. The controller implemented method of claim 7,further including receiving an operator-generated prime mover commandsignal from an operator and temporarily overriding theoperator-generated prime mover command signal with the command signalgenerated by the controller.
 17. The controller implemented method ofclaim 16, wherein the operator-generated prime mover command signal istemporarily overridden while the measured bounce exceeds a predeterminedvalue.
 18. The motor grader of claim 11, wherein the controller isfurther configured to receive an operator-generated prime mover commandsignal from an operator and the command signal generated by thecontroller temporarily overrides the operator-generated prime movercommand signal.
 19. The motor grader of claim 18, wherein the controllertemporarily overrides the operator-generated prime mover command signalwhile the measured bounce exceeds a predetermined value.
 20. The systemof claim 1, wherein the brake is one of a service brake and a parkingbrake.